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History of Hydrogen Sulfide Ambient Air Quality Standard

This page reviewed November 24, 2009.

What is hydrogen sulfide?

Hydrogen sulfide (H2S) is a colorless gas with the odor of rotten eggs. It is formed during bacterial
decomposition of
sulfur-containing organic substances. Also, it can be present in sewer gas and some natural gas, and can be
emitted as the result of geothermal energy exploitation.

Health and Welfare Effects from Ambient Levels of Hydrogen Sulfide

Breathing H2S at levels above the standard will result in exposure to a very disagreeable
odor. In 1984, an ARB committee concluded that the ambient standard for H2S is adequate to protect public health and to significantly reduce odor annoyance.

History of Hydrogen Sulfide Ambient Air Quality Standard

In 1962, the California Board of Public Health adopted an air quality
standard at the "adverse" level for H2S of 0.1 ppm for one hour.

In 1969, the ARB adopted a standard for H2S of 0.03 ppm for a one-hour average
and in 1984, the ARB retained this standard.

For more information on Ambient Air Quality Standards
please contact Linda Smith at (916) 327-8225 or email at lsmith@arb.ca.gov.